1. Field of Invention
This invention relates to systems and methods for improving calibration of a linear array sensor.
2. Description of Related Art
Linear array sensors have been used in binary applications, such as, for example, in a bar code reader. In these applications, each sensor element is used to determine whether light is on or off.
A linear array sensor consists of a series of light sensitive pixels. The pixels are generally characterized by a dark current and a gain. The dark current gives rise to a charge on the sensor when there is no light input. The gain gives the additional charge built up on each pixel per unit of light input.
The dark current and gain of each pixel can be different. When linear array sensors are used for input scanners, the sensitivity of the sensors is calibrated by measuring the response of each pixel under no illumination and the response of each sensor scanning a uniform strip. These two measurements are used to calculate a gain and an offset for the each pixel. This calibration is used to derive a linear equation to relate the charge buildup on each pixel, to the reflection from a surface.